The invention provides a method for renovating a defect surface of a cave body. The method comprises the following steps of: 1, paving a protection element on the defect surface of the cave body; and 2, performing grouting in a seam between the protection element and the cave body. The method has the advantages that the protection element is directly laid on the defect surface of the cave body and is fixed, so that trouble and labor are saved. When the protection element is a corrugated pipe or a corrugated plate, the cost is lower; the structure is simple; and the protection element can be bent to present the required shape according to requirements, so that the laying is convenient, and the workload of construction personnel can be further reduced.